Anion exchange hybrid membranes from PVA and multi-alkoxy silicon copolymer tailored for diffusion dialysis process

Abstract

Abstract Anion exchange hybrid membranes have been prepared from quaternization and sol–gel reaction of multi-alkoxy silicon copolymer (poly(vinylbenzyl chloride-γ-methacryloxypropyl trimethoxy silane) (poly(VBC-co-γ-MPS)) in presence of poly(vinyl alcohol) (PVA). The membranes are of high thermal stability, mechanical strength, and swelling resistance. Thermal degradation temperatures ( T d , defined as the temperature at 5% weight loss) are in the range of 263–283 °C. Tensile strength (TS) ranges from 24.5 MPa to 59.2 MPa and elongation at break ( E b ) is in the range of 25.4–101.2%. The membranes can remain integrity in 65 °C hot water for more than 25 days and the swelling behavior is better suppressed as poly(VBC-co-γ-MPS) content increases. The membranes are tested for diffusion dialysis (DD) recovery of hydrochloric acid (HCl) from the mixture of HCl and ferrous chloride (FeCl 2 ). The temperature for DD process ranged from 20 °C to 60 °C, revealing that the separation factor ( S ) values are in the range of 12.1–35.7, comparable to the values of commercial DF-120 membranes. When the temperature increases from 20 °C to 30 °C, the separation performances are increased. Further increase of temperature increases the dialysis coefficients, but decreases the S value. The membrane structure and properties are correlated with the DD performances.